Stricter standards sought to curb stem-cell confusion

The exact nature and properties of mesenchymal stem cells remain unclear.

STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

Pamela Robey is used to being sent samples by scientists who are anxious to know whether the mesenchymal stem cells (MSCs) they have extracted from fat can be coaxed to turn into either bone or cartilage.

Robey, who directs the Stem Cell Unit at the US National Institutes of Health (NIH), is also used to delivering bad news to many of those who seek her help. They usually are not happy, she says, when her attempts to differentiate the cells produce little more than fatty globules.

To Robey, that disappointment reflects a pervasive misunderstanding about what MSCs are and what they can do one that is fuelled by a lack of information. MSCs have been proposed as treatments for a wide range of ailments including heart and brain injury, joint damage, Crohns disease and multiple sclerosis. But some scientists say that these clinical aspirations have far outrun the basic science. It always seems a little bit like hocus pocus when youre treating everything from skeletal to immunological disorders, says George Daley, director of the Stem Cell Transplantation Program at Boston Childrens Hospital in Massachusetts.

An international group of scientists, industry experts and governmental organizations is trying to introduce scientific clarity to the burgeoning field of MSCs. The group, which met for the first time in late March at NIH headquarters in Bethesda, Maryland, hopes to introduce more rigorous research practices, and eventually to create scientific standards that could guide the commercial development of MSC-based therapeutics. The efforts, applauded by some, are now attracting criticism both from those who advocate MSCs as therapeutics and from those who think that the potential of the cells is oversold.

Even the definition of what constitutes an MSC is a matter of debate. First described in the 1960s as bone-marrow cells that can regenerate bone, the name MSC has expanded to include cells from fat, and from dental and other tissues although early claims that MSCs could give rise to a panoply of different cell types have fizzled out in animal tests. As a first step towards standardization, the group is developing guidelines for research journals to help them cope with the sharp rise in the number of MSC studies being published (see Growth medium). Ideas being floated include requiring authors to define clearly the animal and tissue sources of their cells, and the experimental conditions used to culture them details that are often omitted from published papers.

Source: PubMed

People have to be much more rigorous in defining MSCs, their sources, which tissues you can obtain them from, and what you can use them for, says Paolo Bianco, a stem-cell researcher at the Sapienza University of Rome, who is not involved in the initiative.

Robey, who is on the steering committee of the new working group, is more blunt. Most of the MSC biology is not rigorous, she says. Other stem-cell biologists tend to look down their noses at the field.

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Stricter standards sought to curb stem-cell confusion